Material for organic electroluminescent device and its manufacturing method

ABSTRACT

A process for producing for a material for an organic electroluminescent device having an emission center comprises irradiating a laser beam to implant an emission center-forming compound  3  constituting a source  1  into a target  2  having at least one function selected from an electron-transporting function and a hole-transporting function. According to the process, the laser beam and at least the target are relatively moved with irradiating the beam to form the emission center with a predetermined pattern. Moreover, the source and the target being in contact with each other may be moved relative to the laser beam for forming the emission center with a predetermined pattern. Further, the emission center at an area, corresponding to an interference pattern of an interference light, of the target may be formed by irradiating the interference light of the laser beam.

TECHNICAL FIELD

[0001] The present invention relates to a process for producing amaterial for an organic electroluminescent device by implanting orinjecting an emission center-forming compound by molecular implantationwith laser, a material for an organic electroluminescent device obtainedby this process, and to an organic electroluminescent device (elements)produced with this organic electroluminescent device material.

BACKGROUND ART

[0002] Electroluminescent devices (hereinafter, occasionally referred tosimply as EL devices) have generally been classified as inorganic ELdevices or organic EL devices according to the materials they are madefrom. Some inorganic EL devices utilizing inorganic fluorescentmolecules are in practical use partly, and have been brought intoapplication to the backlight of clocks or the like. Meanwhile, organicEL devices have been desired to be brought into practical use because oftheir being more excellent in high brightness or luminance, highefficiency, and high-speed response than inorganic ones.

[0003] Electroluminescent devices are constituted of a compound orcompounds having an electron-transporting function, a hole-transportingfunction, and an emission center-forming function. As for theirstructures, there have been reported devices of the single-layer modehaving a single layer provided with all the functions mentioned above,and those of the multilayer-mode composed of layers each havingdifferent functions. The principle of light emission is considered to bebased on the phenomenon that electrons or holes injected from a pair ofelectrodes recombine within a light-emitting layer to form excitons,exciting the molecules of a light emissive material for thelight-emitting layer.

[0004] As a compound constituting each layer, a low-molecular weightcompound of high light-emission efficiency, a macromolecular compoundhaving a high physical strength, or the like is employed. When alow-molecular weight compound is used, a film is formed by means of avapor deposition technique, while a macromolecular compound is formedinto a film by coating or applying a solution in many cases.

[0005] Japanese Patent Application Laid-Open No. 96959/1996(JP-A-8-96959) and Japanese Patent Application Laid-Open No. 63770/1997(JP-A-9-63770) disclose organic EL devices comprising a singlelight-emitting layer made of a polymer binder having bothelectron-transporting function and hole-transporting function, withinwhich varieties of fluorescent dyes (or colorants, pigments) aredispersed. These organic EL devises are reported to present, as a whole,white light due to the light emission of each light-emitting compoundindependent of one another. Moreover, as compared with organic ELdevices of the multilayer-mode, those of the single-layer mode arehardly deteriorated in light-emission intensity.

[0006] Fine patterning, particularly multicolor patterning(full-coloration) of these organic EL devices is difficult because, intheir fabrication, a film is formed by means of a solution coatingtechnique in which a solution of a polymer binder and a fluorescentdye(s) dispersed in a specific solvent is applied onto a substrate.

[0007] As multicolor patterning methods, a color filter method, acolor-converting method, the ink-jet method by T. R. Hebner (Appl. Phys.Lett. 72, 5 (1998), p.519), the photobleaching method by Kido, et al,and others have been reported.

[0008] The color filter method or color-converting method has theadvantage of not requiring the patterning of a light-emitting layer, butsuffers deterioration in conversion efficiency caused by the use of afilter. In the ink-jet method, since a pattern formed by ink-jetprinting shows a center-raised, i.e., conical profile and is inferior insmoothness of its surface, it is difficult to provide electrodes thereonuniformly. Moreover, the cross section of the pattern is desired to berectangular, but that of a pattern by ink-jet printing is circular.Further, the dimensions of a pattern largely depend on conditions underwhich the pattern is dried and the concentration of the solution. In thephotobleaching method, only a special emission center-forming compoundwhich loses its fluorescence upon UV oxidation is employable andtherefore colors expressible by EL devices are limited.

[0009] As was described above, in conventional film-forming methods bysolution coating, although it is possible to use a macromolecularcompound with a high physical strength, it is difficult to provide finepatterns. In addition to that, also in the above-described patterningmethods, compounds that can be used are limited, and films havingsurface smoothness suitable for organic EL devices cannot be obtained.

[0010] As the molecular implantation technique, Japanese PatentApplication Laid-Open No. 297457/1994 (JP-A-6-297457) discloses a methodcomprising a step of, with a functional material or a solid materialcontaining a functional material (A) and a solid material into which afunctional component is to be implanted (B) placed such as to face eachother, irradiating a laser pulse thereby to implant the functionalcomponent into the solid material (B). The literature describes that aposition to be implanted of the functional component can be controlledby adjusting an irradiation position of the laser.

[0011] Japanese Patent Application Laid-Open No. 106006/1996(JP-A-8-106006) discloses a method comprising the steps of bringing asource film of an organic macromolecular compound within which dyesabsorptive of a pulse laser are dispersed into tight contact with atarget film of an organic macromolecular compound transmittable of apulse laser, and irradiating a pulse laser from the target film sidewith an intensity of or below the ablation threshold value of the sourcefilm thereby to implant the dyes into the target film. This literaturesays that the molecular implantation technique can be utilized in thefabrication of color filters for use in displays or the like. Moreover,the literature describes that an image can be formed by moving a spotposition of the laser, or the source film and the target film. InExamples of the literature, moving a sample in parallel forms a linearimage.

[0012] Japanese Patent Application Laid-Open No. 150158/2000(JP-A-2000-150158) discloses a process of producing a material for usein an organic electroluminescent device, in which a source containing anemission center-forming compound absorptive of a laser beam is broughtinto contact with a target having an electron-transporting functionand/or a hole-transporting function and the source is irradiated with apulsed laser beam with an intensity not higher than the ablationthreshold of the source thereby to inject the emission center-formingcompound into the target. This specification describes that irradiationof a laser beam through a photomask realizes unrestricted setting of apattern form.

[0013] Accordingly, an object of the present invention is to provide amaterial for organic EL device (particularly, an organic EL device-usefilm) capable of minute and fine patterning even when a macromolecularcompound is used as an EL device-use material and capable of implantingor injecting the emission center-forming compound simply andefficiently, a process for producing the same, and a material for anorganic EL device, which is obtained by the process.

[0014] Another object of the present invention is to provide a materialfor an organic EL device, which is excellent in surface smoothness andhas good contactness with electrodes, and an organic EL device using thesame.

DISCLOSURE OF INVENTION

[0015] The inventors of the present invention made intensive andextensive studies to achieve the above objects, and finally found that,in a molecular implantation technique using a source constituted of anemission center-forming compound, fine patterning is realized simply andeffectively by a process comprising (1) implanting or injecting anemission center-forming compound into a target by relatively moving alaser beam relative to the target, or (2) implanting or injecting anemission center-forming compound into a target with the use of aninterference light of a laser. The present invention was accomplishedbased on the above findings.

[0016] That is, a process for producing a material for an organicelectroluminescent device of the present invention comprises implantingan emission center-forming compound constituting a source into a targethaving at least one function selected from the group consisting of anelectron-transporting function and a hole-transporting function byirradiating a laser beam, and wherein (1) the laser beam and at leastthe target are relatively moved with irradiating the beam to form theemission center with a predetermined pattern, or (2) the emission centerat an area, corresponding to an interference pattern of an interferencelight, of the target is formed by irradiating the interference light ofthe laser beam.

[0017] In the method (1), the source and the target being in contactwith each other may be moved relative to the laser beam for forming theemission center with a predetermined pattern. Moreover, the irradiationof the laser beam may be conducted through a waveguide, or theirradiation of the laser beam may be conducted with the use of anoptical fiber. Further, the laser beam and the target may be relativelymoved with irradiating the beam and with moving the source relative tothe beam for forming the emission center. The laser beam may comprise apulse laser beam. The laser beam and the target may be relatively movedwith synchronizing the beam with a cycle of the pulse.

[0018] In the method (2), a laser beam from a single light source may besplit into a plurality of light paths to cause the interference by anoptical path difference. For example, the interference may be caused byintroducing the laser beam into a hole or a slit, or the interferencemay be caused by reflecting the laser beam through a plurality ofreflection paths.

[0019] The methods (1) and (2) may comprise irradiating the laser beamwith an intensity of or below the ablation threshold value of thesource. The laser beam may comprise a pulse laser beam. The target maycomprise an organic polymer. The target may comprise a compound havingat least one function selected from the group consisting of theelectron-transporting function and the hole-transporting function, and afilm-formable organic polymer. The compound may comprise an oxadiazolederivative having the electron-transporting function, and/or an aromatictertiary amine having the hole-transporting function.

[0020] The present invention also includes a material for an organicelectroluminescent device, which is obtainable by the above-mentionedprocess, and an organic electroluminescent device using the material foran organic electroluminescent device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 is a schematic view explaining the method (1), which is oneembodiment of a technique of implanting or injecting an emissioncenter-forming compound.

[0022]FIG. 2 is a schematic view explaining the method (2), which isanother embodiment of a technique of implanting or injecting an emissioncenter-forming compound.

[0023]FIG. 3 is a schematic sectional view showing one embodiment(single-layer structure) of the organic electroluminescent device of thepresent invention.

[0024]FIG. 4 is a schematic sectional view showing another embodiment(multilayered structure) of the organic electroluminescent device of thepresent invention.

[0025]FIG. 5 is a schematic sectional view showing further anotherembodiment (multilayered structure) of the organic electroluminescentdevice of the present invention.

[0026]FIG. 6 is a schematic sectional view showing still anotherembodiment (multilayered structure) of the organic electroluminescentdevice of the present invention.

[0027]FIG. 7 is a schematic view explaining another production processaccording to the method (1) of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0028] [Source (A)]

[0029] The source need only contain at least an emission center-formingcompound, and may be comprised of the emission center-forming compoundsingly, or of the emission center-forming compound and a binder.

[0030] (Emission Center-forming Compound)

[0031] As the emission center-forming compound, a compound havingfunction as an emission center-forming compound for organic EL deviceand being absorptive of laser beams, in particular a compound emitting alight by being excited by an electron and/or a hole (positive hole), canbe utilized. The emission center-forming compound includes aheterocyclic compound containing at least one hetero atom selected fromoxygen, nitrogen and sulfur atoms [e.g., abis(C₁₋₆alkyl-benzoxazoyl)thiophene such as2,5-bis(5-tert-butyl-2-benzoxazoyl)-thiophene, nile red, a coumarin suchas coumarin 6 and coumarin 7, a4-(dicyanoC₁₋₄alkylene)-2-C₁₋₄alkyl-6-(p-diC₁₋₄alkylaminostyryl)-4H-pyransuch as4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran, andquinacridone]; a condensed polycyclic hydrocarbon such as rubrene andperylene; a tetraC₆₋₁₂aryl-1,3-butadiene such as1,1,4,4-tetraphenyl-1,3-butadiene (TPB); abis(2-(4-C₁₋₄alkylphenyl)C₂₋₄alkynyl)benzene such as1,4-bis(2-(4-ethylphenyl)ethynyl)benzene; and abis(2,2′-diC₆₋₁₂arylvinyl)biphenyl such as4,4′-bis(2,2′-diphenylvinyl)biphenyl. Among them, nile red and coumarin6 are particularly preferable.

[0032] The structures of nile red and coumarin 6 are shown below:

[0033] The wavelength of light emitted by nile red is 580 nm (emissionof red light) and that of coumarin 6 is 490 nm (emission of greenlight).

[0034] These emission center-forming compounds may be used either singlyor in combination.

[0035] (Binder) As the binder, usually, a resin having film-formingproperties (e.g., a thermoplastic resin, a thermosetting resin) can beused.

[0036] Examples of the thermoplastic resin are a olefinic resin such asa polyethylene, a polypropylene, an ethylene-propylene copolymer and apolybutene; a styrenic resin such as a polystyrene, a rubber-modified(or rubber-containing, rubber-reinforced) polystyrene (HIPS), anacrylonitrile-styrene copolymer and an acrylonitrile-butadiene-styrenecopolymer; an acrylic resin [for example, a homo- or copolymer of a(meth)acrylic monomer (e.g., a C₁₋₆alkyl (meth)acrylate such as methyl(meth)acrylate, ethyl (meth)acrylate and butyl (meth)acrylate, ahydroxyC₂₋₄alkyl (meth)acrylate such as hydroxyethyl (meth)acrylate andhydroxypropyl (meth)acrylate, glycidyl (meth)acrylate, (meth)acrylicacid, and (meth)acrylonitrile), a copolymer of the (meth)acrylic monomerand a copolymerizable monomer (e.g., an aromatic vinyl monomer such asstyrene) (for example, a methyl methacrylate-styrene copolymer)]; avinyl alcohol-series polymer such as a polyvinyl alcohol and anethylene-vinyl alcohol copolymer, a vinyl-series resin such as apolyvinyl chloride, a vinyl chloride-vinyl acetate copolymer, apolyvinylidene chloride, a polyvinyl acetate, an ethylene-vinyl acetatecopolymer and a polyvinyl acetyl; a polyamide-series resin such as a6-nylon, a 6,6-nylon, a 6,10-nylon and a 6,12-nylon; a polyester resin[for example, an alkylene arylate-series resin such as a polyalkyleneterephthalate (e.g., a polyethylene terephthalate and a polybutyleneterephthalate) and a polyalkylene naphthalate, or alkylene arylatecopolyester resin]; a fluorine-containing resin; a polycarbonate; apolyacetal; a polyphenylene ether; a polyphenylene sulfide; a polyethersulfone; a polyether ketone; a thermoplastic polyimide; a thermoplasticpolyurethane; and a norbornene-series polymer.

[0037] Exemplified as the thermosetting resin are a phenolic resin, anamino resin (e.g., a urea resin and a melamine resin), a thermosettingacrylic resin, an unsaturated polyester resin, an alkyd resin, a diallylphthalate resin, an epoxy resin, and a silicone resin.

[0038] The binder may be used singly or in combination.

[0039] The content of the emission center-forming compound in the sourceis not particularly limited to a specific content, and is about 0.1 to100% by weight, preferably about 1 to 90% by weight, and more preferablyabout 5 to 80% by weight. Moreover, in the case where the sourcecomprises an emission center-forming compound and a binder, the contentof the emission center-forming compound is not particularly limited to aspecific content, and for example is about 0.1 to 60 parts by weight,preferably about 1 to 30 parts by weight, and more preferably about 3 to20 parts by weight relative to 100 parts by weight of the binder.

[0040] The source is usually used in the form of a film. Moreover, thesource may be a film or coat of the above emission center-formingcompound singly formed on the substrate or the target, or that of theabove emission center-forming compound and the binder. In the case ofirradiating a laser beam from the source side, the substrate need onlybe sufficiently transparent to transmit laser beams, examples of whichare a glass plate such as a soda glass, a no-alkali glass, and a quartzglass; and a polymer sheet or film of a polyester, a polystyrene, anacrylic resin, a vinyl-series resin (e.g., a polyvinyl acetal), apolysulfone, and of a polyethersulfone.

[0041] There is no particular restriction as to a process of forming asource film, and a conventional process [e.g., dry processes such asvapor deposition (vacuum deposition), wet coating processes that use asolvent, such as spin coating, dip coating and die coating] may beemployed. Incidentally, the film may be formed in accordance with aconventional film-forming process (e.g., casting method and extrusionmethod).

[0042] If necessary, into the coating agent (coating liquid) for forminga coat (coating film) of the source, i.e., the source may beincorporated a solvent (e.g., water; alcohols such as methanol andethanol; esters such as ethyl acetate and isobutyl acetate; ketones suchas acetone and methyl ethyl ketone; aromatic hydrocarbons such astoluene; alicyclic hydrocarbons such as cyclohexane; halogenatedhydrocarbons such as chloroform and chlorobenzene; ethers; cellosolves;carbitols). The thickness of the film (coat) may be about 0.01 to 50 μm,preferably about 0.1 to 30 μm, and more preferably about 0.5 to 20 μm.

[0043] Moreover, the source may not be defined in a pattern, or thesource itself may be defined in a given pattern. A film (layer, deposit)defined in a pattern, if necessary, on a substrate (base material) or atarget may be used as a source. For example, a film or sheet comprisingan emission center-forming compound may be patterned by punching orother means to give a source. Moreover, the substrate need only besufficiently transparent to transmit laser beams, examples of which area glass plate such as a soda glass, a no-alkali glass, and a quartzglass; and a polymer sheet or film of a polyester, a polystyrene, anacrylic resin, a vinyl-series resin (e.g., a polyvinyl acetal), apolysulfone, and of a polyethersulfone.

[0044] In the case of defining into a pattern of a source, the patternis selected according to the intended application, and for example maybe any of a one dimensional pattern [a dotted pattern, a lined pattern(e.g., parallel, random, grid)] and a two-dimensional pattern [a planepattern (e.g., circular, oval, polygonal such as triangle and rectangle,star-shaped)]. The predetermined pattern is provided on the substrate orthe target by, for example, printing such as screen printing, ink jetsystem, melt or thermal transfer, or vapor deposition (sublimationprinting) involving masking.

[0045] [Target (B)]

[0046] Insofar as the target has at least one function selected from theelectron-transporting function and the hole-transporting function, thereis no particular restriction, and the target may be (I) a resin havingat least one function selected from the electron-transporting functionand the hole-transporting function, or (II) a resin compositioncomprising a resin which inherently has neither theelectron-transporting function nor the hole-transporting function butgiven with at least one function selected from these. As the resins forthe use of (I) and (II), resins (binder) having film- or coat-formingproperties are preferred. Moreover, when the laser beam is incident fromthe side of the target, the target is transmittable of the laser beam.

[0047] Exemplified as the resin (I) having at least one functionselected from the electron-transporting and hole-transporting functionsis a polyphenylenevinylene [for example, a homo- or copolymer of aC-₆₋₁₂arylenevinylene, which may have a substituent (e.g., a C₁₋₁₀alkoxygroup), such as a polyphenylenevinylene, apoly(2,5-dimethoxyphenylenevinylene) and a polynaphthalenevinylene]; apolyphenylene (in particular, a polyparaphenylene) [for example, a homo-or copolymer of a phenylene, which may have a substituent (e.g., aC₁₋₁₀alkoxy group), such as a polyparaphenylene and apoly-2,5-dimethoxyparaphenylene]; a polythiophene [a homo- or copolymerof a polyC₁₋₂₀alkylthiophene such as a poly(3-alkylthiophene), apolyC₃₋₂₀cycloalkylthiophene such as a poly(3-cyclohexylthiophene), anda C₆₋₂₀arylthiophene, which may have a substituent (e.g., a C₁₋₁₀alkylgroup), such as a poly(3-(4-n-hexylphenyl)thiophene)]; a polyfluorenesuch as a polyC₁₋₂₀alkylfluorene; a vinyl-series polymers having atleast one functional group selected from a hole-transporting functionalgroup and an electron-transporting functional group in the main or sidechain, such as a poly-N-vinylcarbazole (PVK), apoly-4-N,N-diphenylaminostyrene, apoly(N-p-diphenylamino)phenylmethacrylamide), apoly(N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diaminomethacrylamide)(PTPDMA) and a poly-4-(5-naphthyl-1,3,4-oxadiazole)styrene; apolyC₁₋₄alkylphenylsilane such as a polymethylphenylsilane; a polymerhaving an aromatic amine derivative in a side or main chain thereof; anda copolymer thereof. The resin can be used either singly or incombination. The preferred target includes a copolymer comprising apoly-N-vinylcarbazole or N-vinylcarbazole as a main component (not lessthan 50% by weight, and preferably about 60 to 98% by weight), and apolymer having an aromatic amine derivative in a side chain or mainchain thereof.

[0048] PVK is amorphous and excellent in heat resistance (glasstransition temperature Tg: 224° C.). The degree of polymerization of PVKis not particularly restricted, and is, for example, about 200 to 5,000(e.g., 300 to 3,000), and preferably about 500 to 2,000 (e.g., 500 to1,500).

[0049] Further, if needed, the electron- or hole-transporting functionmay be given to the resin (I).

[0050] Examples of the compound having an electron-transporting functionare an oxadiazole derivative [for example, an oxadiazole derivativehaving a C₆₋₂₀aryl group which may have a substituent, such as2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD),2,5-bis(1-naphtyl)-1,3,4-oxadiazole (BND),1,3-bis[5-(4-tert-butylphenyl)-1,3,4-oxadiazole)]benzene (BPOB),1,3,5-tris[5-(4-tert-butylphenyl)-1,3,4-oxadiazole]benzene (TPOB) and1,3,5-tris[5-(1-naphtyl)-1,3,4-oxadiazole]benzene (TNOB)]; adiphenoquinone [for example, a diphenoquinone which may have asubstituent (e.g., a C₁₋₁₀alkyl group), such as3,5,3′,5′-tetrakis-tert-butyldiphenoquione];1,2,3,4,5-pentaphenyl-1,3-cyclopentadiene (PPCP); and a quinolinic acidcomplex such as a tris(8-quinolinorato)aluminium (III) complex, abis(benzoquinolinolato)beryllium complex and atris(10-hydroxybenzo[h]quinolilate)beryllium complex. Particularly PBDis preferred.

[0051] As the compound having a hole-transporting function, there may beexemplified an aromatic tertiary amine such asN,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD),N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4,4′-diamine (NPD),1,1-bis[(di-4-tolylamino)phenyl]cyclohexane,N,N,N′N′-tetra(3-methylphenyl)-1,3-diaminobenzene (PDA),4,4′,4″-tris(3-methylphenylphenylamino)triphenylamine (m-MTDATA),4,4′,4″-tris(1-naphthylphenylamino)triphenylamine(1-TNATA),4,4′,4″-tris(2-naphthylphenylamino)triphenylamine (2-TNATA),4,4′,4″-tri(N-carbazolyl)triphenylamine (TCTA),1,3,5-tris[4-(3-methylphenylphenylamino)phenyl]benzene (m-MTDAPB) andtriphenylamine; and a phthalocyanine.

[0052] The above compound can be used either singly or in combination.Incidentally, among these compounds, a compound emitting a light bybeing excited by an electron and/or a hole may be used as an emissioncenter-forming compound.

[0053] The proportion of the above-mentioned component contained in theresin (I) (e.g., PVK) can be selected within the range not adverselyaffecting the functions qualifying the resin as an organic EL devicematerial, and is, for example, about 10 to 300 parts by weight, andpreferably about 20 to 200 parts by weight relative to 100 parts byweight of the resin (I).

[0054] When the target is constituted of the resin (I) and the compounddescribed above, the organic EL device which will later be described canbe made so as to have a single-layered structure, and the organic ELdevice so fabricated not only has improved luminous efficiency but alsois economically advantageous.

[0055] There is no specific restriction as to a resin to be used in theresin composition (II), and such a variety of above-mentioned bindershaving the film-forming properties (e.g., thermoplastic resins,thermosetting resins) are available. At least one function selected fromthe electron-transporting function and the hole-transporting functionmay be given to these resins. Exemplified as the compound(s) to be usedto provide the electron- or hole-transporting function are compoundssimilar to those listed above.

[0056] The amount of the compound having an electron-transporting orhole-transporting function to be added is about 10 to 300 parts byweight (e.g., about 10 to 200 parts by weight) and preferably about 20to 100 parts by weight (e.g., about 20 to 80 parts by weight) relativeto 100 parts by weight of the binder resin.

[0057] The resin (I) and the resin composition (II) may be used incombination, and such combined material may further be given at leastone function selected from the electron-transporting function and thehole-transporting function.

[0058] Incidentally, a form (shape or configuration) of the target isnot particularly limited to a specific form, and usually, is used in theform of a film. Moreover, the target is formed in the same manner as inthe source, and usually is formed on the above-mentioned substrate.

[0059] [Production Process of Material for Organic EL Device (MolecularImplantation)]

[0060] The process for producing materials for organic EL devices of thepresent invention comprises implanting an emission center-formingcompound in a source into the target by irradiating (or exposing) alaser beam, and wherein (1) the laser beam and at least the target arerelatively moved with irradiating the beam to form the emission centerwith a predetermined pattern, or (2) the emission center at an area,corresponding to an interference pattern of an interference light, ofthe target is formed by irradiating the interference light of the laserbeam. The laser beam may be irradiated from the source (A) side or thetarget (B) side. As the target, a film is usually employed to produce afilm for an organic EL device. Moreover, the target may be brought intocontact with the source.

[0061] Exemplified as the laser beam to be used in the present inventionare, though it differs with the species of the emission center-formingcompound to be used, those having an oscillation wavelength within therange of 190 to 1,100 nm. When using a pulse laser beam (pulsed laserbeam), the frequency is about 0.5 to 50 Hz and preferably about 0.5 to30 Hz. Moreover, although the pulse width varies with the wavelength ofthe laser beam, it is about 10 ps to 10 μs (e.g., about 10 ps to 1 μs),preferably about 50 ps to 100 ns (e.g., about 100 ps to 50 ns). Theshorter the pulse width (duration) is, the less the decomposition of theemission center-forming compound occurs, and therefore, the emissioncenter-forming compound is hardly damaged.

[0062] Exemplified as the source of the laser beam are gas laser [ArFexcimer laser (193 nm), KrF excimer laser (248 nm), XeCl excimer laser(308 nm), XeF excimer laser (351 nm), nitrogen laser (337 nm)], dyelaser [nitrogen laser, excimer laser, or YAG laser excitation, 300 to1,000 nm], solid-state laser [(Nd:YAG excitation, semiconductor laserexcitation, etc.), ruby laser (694 nm), semiconductor laser (650 to 980nm), tunable diode laser (630 to 1,550 nm), titanium-sapphire laser(Nd:YAG excitation, 345 to 500 nm, 690 to 1,000 nm), and Nd:YAG laser(FHG: 266 nm, THG: 354 nm, SHG: 532 nm, fundamental wave: 1,064 nm)].

[0063] In the production process of the present invention, irradiationof a laser beam with an intensity of or below the ablation threshold ofthe source (that is, the emission center-forming compound or binder)makes it possible to effectively implant the emission center-formingcompound into the target. The amount of the emission center-formingcompound to be implanted can be controlled by regulating, e.g., theintensity and wavelength of the laser beam, and the number of times thelaser beam is shot.

[0064] The ablation threshold of the source (A) varies with the speciesof the emission center-forming compound constituting the source.Moreover, the ablation threshold also depends on the wavelength andpulse width of the laser beam. Therefore, in the present invention, theablation threshold is defined as follows.

[0065] The term “ablation threshold value” used in the present inventionis defined as a term referring to, assuming that a source is irradiatedwith one shot of a laser beam and observed by a contact-type (mode)surface morphology measuring apparatus (e.g., DEKTAK3030ST, manufacturedby SLOAN), the lowest laser intensity (mJ/cm²) measured on the surfaceirradiated with the laser beam at which the surface might suffer changesin surface conditions by a depth of 50 nm or more. The source and thelaser beam are the same as those employed in the present invention.

[0066] Hereinafter, the process of the present invention for producing amaterial for use in an organic EL device (particularly, films for use inorganic EL devices) will be described with reference to Figures. FIG. 1shows a schematic view showing a production process in the method (1) ofthe present invention. FIG. 2 shows a schematic view showing aproduction process in the method (2) of the present invention. A source1, a target 2, an emission center-forming compound 3, a substrateresided in the target side 4, a substrate resided in the source side 5,and a hole 6 are illustrated in Figures.

[0067] According to FIG. 1, firstly, the source 1 formed on thesubstrate 5 is brought into contact with or closely contact with thetarget 2 formed on the substrate 4, and irradiated with a laser beamwith an intensity of or below the ablation threshold of the source fromthe source 1 side with relatively moving the beam relative to thetarget. The emission center-forming compound, which absorbed the laserbeam, obtains high translational energy and is injected or implantedinto the target 2 without being decomposed, and a material for anorganic EL device (particularly, a film) is obtained.

[0068] According to FIG. 2, firstly, the source 1 formed on thesubstrate 5 is brought into contact with or closely contact with thetarget 2 formed on the substrate 4, and irradiated with a laser beamwith an intensity of or below the ablation threshold of the source fromthe source 1 side with causing an interference by introducing the beaminto a hole 6. The emission center-forming compound, which absorbed thelaser beam, obtains high translational energy and is injected orimplanted into an area, corresponding to an interference pattern of theinterference light, of the target 2 without being decomposed, and amaterial for an organic EL device (particularly, a film) is obtained.

[0069] In the methods (1) and (2), the laser beam is shot about 1 to 200times, preferably about 1 to 150 times, and more preferably about 1 to100 times (e.g., about 5 to 50 times). Moreover, the laser beam may beshot from the target side. Incidentally, the source may be formed on thetarget directly as a surface layer. The source formed on the target canbe removed from the target easily after implanting the emission-centercompound. Moreover, the source may be formed by a surface layerremovable or separable from the target.

[0070] The substrate to be used need only have sufficient transparencyto transmit a laser beam, examples of which are the above-mentionedsubstrates (e.g., a glass plate such as a quartz glass, a polymer sheetor film). As the substrate, a substrate used on forming of a source or atarget film may be employed without modification, or a substrateproduced freshly may be employed.

[0071] In the process for producing the material for the organic ELdevice of the present invention, there is no particular restriction asto the shape that the cross-section of the laser beam takes, and it maybe circular, oval, or polygonal (e.g., triangle, rectangle). The averagebeam area of the laser beam is not particularly limited to a specificarea, and can be selected from a wide range for any purpose. Forexample, the area is about 0.01 to 5,000 μm², preferably about 0.1 to4,000 μm², and more preferably about 1 to 3,000 μm². Incidentally, inthe method (1), a pattern may be defined or formed by narrowing an areaof a laser beam down a desired size and scanning a predeterminedpattern, or an emission center-forming compound may be implanted into atarget in a predetermined area by enlarging the area of the laser beamto use a source having a predetermined pattern or relatively scanning alaser beam through a photomask.

[0072] Moreover, a plurality of sources having emission center-formingcompounds different from one another may be employed. For example, theuse of a compound capable of emitting a light in visible light region (acompound capable of emitting a light such as yellow, red, green or blue)realizes a desired emission color. Moreover, in the method (2), the useof a plurality of sources realizes that an emission light such as red,green and blue can be arranged or arrayed as corresponding to aninterference fringe or pattern (e.g., vertical stripe, delta arrangementand tetragonal arrangement). Therefore, the present invention makes itpossible to obtain materials for organic EL devices capable of emittingvarious colors and having various patterns.

[0073] The method (1) has a characteristic that the laser beam and atleast the target are relatively moved for implanting an emissioncenter-forming compound of a source into the target with a predeterminedpattern. In the method (1), the source and the target are contacted witheach other and positioned, and the source may be moved with the target,or the source may be movable relative to the target relatively. In thecase where the source and the target are contacted with each other, anirradiation of a laser beam may, for example, be conducted either by(1-1) moving a light path of the laser beam relative to the source andthe target, or by (1-2) moving the source and the target relative to alight path of the laser beam. Furthermore, in these methods, the lightpath of the laser beam is movable not only by moving a laser lightsource relatively but also (1-3) by using means for controlling thelight path.

[0074] The means for controlling the light path includes a process ofutilizing physical means or physico-optical means [for example, anoptical device (or optical member) such as an optical fiber, areflection mirror (e.g., a total reflection mirror, a half reflectionmirror), a lens (e.g., condenser) and a deflecting prism, or means incombination with them], a process of utilizing electro-optical means[(e.g., applying a voltage to an electro-optical crystal (a birefringentcrystal)] to move a light path of a light beam of a waveguide, and aprocess of utilizing supersonic waves. Incidentally, in a process ofutilizing supersonic waves, the waveguide can be moved by using acrystalline material (such as water, a chalcogenide-series vitreousmaterial, PbMoO₄, TeO₂, Ge, LiNbO₃ and GaP) as a medium, and applying avoltage to the medium through a piezoelectric thin film transducer(e.g., a piezoelectric device such as LiNbO₃ and ZnO) to generatesupersonic waves to the medium.

[0075] In the physical means or physico-optical means, when the lightpath of the laser beam is moved by utilizing an optical fiber, adiffusion loss of the laser beam can be reduced, and efficient and finepatterning can be conducted simply.

[0076] Incidentally, according to the method (1), the laser beam iscapable of moving relatively and two-dimensionally relative to at leasta target. Therefore, an emission center-forming compound of a source canbe implanted into a target with a predetermined pattern efficiently, andthe emission center can be formed in the form of a two-dimensionalpattern.

[0077] For example, precise positioning is realized easily andtwo-dimensional fine patterning is realized, by bringing a source intocontact with a target, fixing them on a table movable for X-Y axialdirection with turning up a target surface or source surface, setting upa sensor for detecting a displacement from a reference position of thetarget (or source) to X-axial and Y-axial directions, and moving thetable to X-axial and Y-axial directions in response to a detectionsignal obtained from the sensor. Incidentally, if necessary, by settingup a memory memorized a data of the pattern, and a controller for movingthe laser and/or the table in response to the pattern signal, patterningcan be conducted simply.

[0078] In the case where a pulse laser is used as a laser beam, a targetand a laser beam are relatively shifted by relatively moving the laserbeam relative to at least the target according to the above-mentionedmanner by synchronizing with a pulse cycle, and an emissioncenter-forming compound can be implanted into a target efficiently. Inthe process, the target may be moved relative to the laser beam, andusually synchronizing with pulse cycle controls the laser beam or alight path of the laser beam.

[0079] Further, according to the present invention, a laser beam may berelatively moved relative to at least a target, and a source may bemoved relative to the laser beam. Incidentally, by repeated irradiationof a laser beam to the same site of the source is consumed an emissioncenter-forming compound, and is unable to form an emission centerefficiently. In such a case, relative movement of the laser beam and thetarget with irradiating the laser beam and with relatively moving thesource relative to the laser beam realizes that an emissioncenter-forming compound is implanted into the target effectively andefficiently.

[0080] For example, a plurality of emission centers different from eachother in emission color (e.g., emission centers having full-color) canbe also formed efficiently. According to the method (1), a plurality ofareas comprising each of emission center-forming compounds (e.g., anarea comprising a yellow emission center-forming compound, an areacomprising a red emission center-forming compound, and an areacomprising a blue emission center-forming compound) may be formed into asource. The use of such a source ensures that a plurality of emissioncenters different from each other in emission color can be formed withuse of a single source by relatively moving the source relative to thelaser beam and/or the target toward X-axial and/or Y-axial direction(s).

[0081]FIG. 7 shows a schematic view explaining another productionprocess according to the method (1). In the embodiment, a productionprocess of a red emission center comprises moving a light path of alaser beam (light source or waveguide) relative to a target toward alongitudinal direction and/or a lateral direction, irradiating (orexposing) the laser beam to an area comprising a green emissioncenter-forming compound of a source to form a green emission center intothe target, moving the source relative to the laser beam, thenirradiating the laser beam to an area comprising a red emissioncenter-forming compound to form a red emission center into the target.Further, a blue emission center is produced in the same manner asdescribed above, and a material for an organic EL device capable ofemitting a full-colored light can be produced. Moreover, according tothe method, a pulse laser is irradiated (or emitted) to the targetthrough the source with scanning toward a longitudinal direction and/ora lateral direction, and the source 1 and the target 2 is capable ofcontacting with each other at an irradiation site of the laser beam.Incidentally, the source 1 is movable to X-axial and/or Y-axialdirection(s) by means of a feed apparatus.

[0082] In this way, when the source is moved relative to the laser beam,the use of a single source realizes that a plurality of emission centersdifferent from each other in emission color are produced. An emissioncenter-forming compound is used without wasting, the emissioncenter-forming compound is implanted efficiently, and the process isadvantageous in terms of cost. Moreover, the source may be formed withan undefined length film or the like. The use of such a film realizes acontinuous or successive production of an emission center-formingcompound.

[0083] The method (2) has a characteristic that the utilization of highcoherence (coherency) of a laser beam realizes a production of anemission center into an area corresponding to an interference pattern ofan interference light in the target by the interference light of thelaser beam. Incidentally, “interference” also includes diffraction(considered as an interference of small wave (secondary wave) by thePrinciple of Huygens) (“Basis and Experiment of Laser”, KoreiwaMatsudaira, issued by Kyoritsu Shuppan, Co., Ltd., the 11th edition,page 54).

[0084] In the method (2), an interference of a laser beam may beobtained from optical path difference caused by splitting a laser beamfrom the single light source into a plurality of light paths. A processfor interfering with a laser beam is not limited to one using a hole asshown in FIG. 2, and for example, may be conducted either by (2-1)introducing a laser beam into a hole or a slit to cause an interference,or by (2-2) reflecting a laser beam through a plurality of reflectionpaths capable of reflecting to cause an interference.

[0085] In the hole or the slit, a slit width (in case of the hole, theaverage hole diameter) is not particularly limited, and is about 0.01 to100 mm, preferably about 0.1 to 10 mm, and more preferably about 0.5 to5 mm (e.g., about 0.5 to 3 mm). Incidentally, there is no particularrestriction as to a shape of the hole, and may be mentioned circular,oval, or polygonal (e.g., triangle, rectangle). In the case where theshape of the hole is noncircular, the average diameter means an averagediameter of circumscribed circle of the hole.

[0086] Incidentally, the hole and the slit may be a single hole or slit,or each of them may be used plurally or in combination (e.g., doubleslit). Moreover, the hole and the slit may be used in combination. Alaser beam guided by the hole or the slit is interfered by the opticalpath difference (in case of using a single hole or slit, diffracted),and interference fringe (or diffraction fringe) occurs.

[0087] In the method (2-2), a mirror (e.g., a semitransparent mirror, areflecting mirror) is usually employed in order to reflect a laser beam.In particular, the use of a semitransparent mirror ensures that anoptical path difference between a transmitted light and a reflectedlight generates simply. For example, the process comprises beingincident a laser beam on a semitransparent mirror, which is disposedwith gradient of a predetermined angle from an incident direction of thelaser beam, transmitting part of the laser beam and reflecting theresidual laser beam in an orthogonal direction to the incident directionof the laser beam. The transmitted light is incident on a firstreflection mirror apart from the semitransparent mirror at apredetermined distance. On the other hand, the reflected light isincident on a second reflection mirror apart from the semitransparentmirror at a distance different from the above distance. A laser beam,which is obtained by reflecting with use of the first and the secondreflection mirror, going through a different reflection path and beingincident on the semitransparent mirror again, is incident on the target,and as a result, an interference occurs by an optical path difference.Moreover, by adjusting a distance between the transparent mirror and thereflection mirror, a desired interference pattern can be obtained.

[0088] Incidentally, each of the semitransparent mirror(s) and thereflection mirror(s) may be used singly or in combination. In order tobe incident the laser beam on the semitransparent mirror efficiently,the laser beam may be made parallel pencil through a lens (such as atelemeter lens) and may be incident on the semitransparent mirror.

[0089] In such a method (2-1) or (2-2), a distance between interferencefringes, or a shape (or form) of interference fringe can be adjusted byselecting parameters such as a hole diameter or a slit width and amirror position suitably, and by varying an optical path distance. Adesired interference pattern (interference fringe) can be obtainedwithout through a mask and the like. In particular, when the holediameter or the slit width is turned down to a wavelength of the laserbeam, interference fringe having a fine distance can be obtained, andfine patterning of an emission center-forming compound can be conductedeasily. Further, since the interference fringe is usually a concentricpattern (symmetric figure) in which a center energy is most highest, theamount to be implanted of the emission center-forming compound can beadjusted.

[0090] Moreover, the production process of the present inventionrealizes that an emission center-forming compound is implanted into atarget not in a dispersed or diffused form but in a step form (that is,an oblong form, in which the depth of the compound implanted into thetarget is uniform). The depth is varied depending on a kind or speciesof the emission center-forming compound or the target, or intensity of alaser beam, and for example, is about 10 to 300 nm, preferably about 15to 200 nm, and more preferably about 20 to 100 nm. Moreover, irradiationof the laser beam with an intensity of or below the ablation thresholdvalue ensures that an emission center-forming compound is implantedefficiently without deterioration in surface smoothness of a materialfor an organic EL device.

[0091] [Organic Electroluminescent Device]

[0092] The organic electroluminescent device of the present inventioncomprises a material for an organic EL device obtained by the processdescribed above (particularly, a light-emitting layer constituted of atarget film into which an emission center-forming compound has beenimplanted) and a pair of electrodes.

[0093] As the anode, a transparent electrode formed by vacuum depositionor other methods (e.g., indium-tin-oxide (ITO) electrode) or the like isemployed, and a highly conductive metal having a small work function(e.g., magnesium, lithium, aluminum, or silver) is used as the cathode.In the case where magnesium is employed as the cathode, the magnesiummay be coevaporated with a small amount of silver (e.g., 1 to 10% byweight) for improving the adhesion with an organic EL device-use film.

[0094] When the light-emitting layer has both the electron-transportingfunction and the hole-transporting function, the organic EL device ofthe present invention can be made so as to have a single-layeredstructure. When the light-emitting layer is lacking in either theelectron-transporting function or the hole-transporting function or whenattempting to improve each function, a layer having the desired functionmay be laminated on the light-emitting layer by a conventional vapordeposition technique or a solution coating technique. These layers maybe of low-molecular weight compounds or macromolecular compounds, andeither will do. The organic EL device can take, for example, asingle-layer structure or a multilayer-structure as shown in FIGS. 3 to6.

[0095] That is, as illustrated in FIG. 3, the organic EL device may beone composed of a substrate 10, an anode 11 formed thereon, alight-emitting layer 12, and a cathode 13 laminated on the anode in thisorder, or, as shown in FIG. 4, it may be one composed of a substrate 20,an anode 21 formed thereon, a hole-transporting layer 24, alight-emitting layer 22, and a cathode 23 laminated on the anode in thisorder. Further, as shown in FIG. 5, the organic EL device may be onecomposed of a substrate 30, an anode 31 formed thereon, a light-emittinglayer 32, an electron-transporting layer 35, and a cathode 33 laminatedon the anode in this order, or, as shown in FIG. 6, it may be onecomposed of a substrate 40, an anode 41 formed thereon, ahole-transporting layer 44, a light-emitting layer 42, anelectron-transporting layer 45, and a cathode 43 laminated on the anodein this order.

[0096] The thickness of each of the layers constituting the organic ELdevice is not particularly limited, and is about 10 nm to 1 μm (e.g.,about 10 to 500 nm), preferably about 30 to 300 nm, more preferablyabout 30 to 200 nm, particularly about 5 to 20 nm. When films areemployed, the thickness of each film can be selected within the rangesmentioned above.

[0097] Exemplified as the substrate are those mentioned above, such assubstrates having sufficient transparency to transmit laser beams (e.g.,a glass plate, such as a soda glass, a no-alkali glass, and a quartzglass, a polymer sheet or film of a polyester, a polysulfone, and apolyethersulfone). For the fabrication of flexible organic EL devices,the use of polymer films are preferred. As the substrate, a substrateused on the molecular implantation may be employed without modification,or a substrate produced freshly may be employed.

[0098] According to the present invention, fine and multicolorpatterning of an organic EL device made with macromolecular compoundswhich had long been difficult to realize was made possible. Further,since the material for the organic EL device (particularly, film fororganic EL device) of the present invention is excellent in surfacesmoothness, it makes closely contact with the electrodes, and theorganic EL device of the present invention is free from the irregularityin voltage caused upon application of voltage because of the emissioncenter-forming compound implanted therein step-like.

INDUSTRIAL APPLICABILITY

[0099] The present invention ensure that high positioning is conductedby relatively moving a laser beam relative to at least a target, finepatterning is conducted simply, and the use of an optical fiber realizeshigh-precision fine patterning. Moreover, an efficient implantation ofemission center-forming compound is realized by relatively moving alaser beam and at least a target with moving a source relative to thelaser beam.

[0100] Moreover, according to the present invention, the utilization ofhigh coherence (coherency) of a laser beam realizes a production of anemission center into an area corresponding to an interference pattern byan interference light of the laser beam. Since the interference patterncan be adjusted to a desired shape (form) and distance by selecting aparameter such as a hole diameter and a slit width suitably, finepatterning can be conducted simply.

EXAMPLES

[0101] The following examples are intended to describe this invention infurther detail and should by no means be interpreted as defining thescope of the invention.

Example 1

[0102] (Preparation of Source Film)

[0103] A polybutylmethacrylate (manufactured by Aldrich ChemicalCompany, Inc., molecular weight: 3.4×10⁵) containing 5% by weight ofcoumarin 6 (manufactured by Nippon Kankoh Shikiso, K.K.) was dissolvedin chlorobenzene, and a layer having 1 μm thick was produced on a quartzsubstrate by a spin coating method.

[0104] (Preparation of Target Film)

[0105] 500 mg of a poly-N-vinylcarbazol having a hole-transportingfunction (PVK: manufactured by Kanto Kagaku, K.K.) and 500 mg of2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole having anelectron-transporting function (PBD: manufactured by Aldrich ChemicalCompany, Inc.) were dissolved in 10 ml of 1,2-dichloroethane. A coatlayer of indium-tin-oxide (ITO) was formed on a glass substrate. Usingthe above-mentioned 1,2-dichloroethane solution, on the ITO coat layerthus obtained was formed a 100 nm thick target film having the electronand hole-transporting functions by dip coating.

[0106] (Molecular Implantation)

[0107] An emission center-forming compound was implanted into a patternhaving an area of 20 mm² by bringing thus obtained source film intocontact with thus obtained target film, fixing them on a table movablefor X-axial and Y-axial directions with a target film surface turningup, using a laser processing apparatus capable of oscillating XeFexcimer laser (wavelength: 351 nm) having 10 ns of a pulse width at 20mm² of a beam area, and moving the table relative to the laser beamtoward X-Y-axial direction.

[0108] (Organic EL Device)

[0109] A 200 nm thick Al/Li electrode (manufactured by Kohjundo Kagaku,K.K.; Li content: 0.78% by weight) was formed on the molecular-implantedtarget film (test piece 1) by vacuum deposition to provide an organic ELdevice 1.

[0110] With the ITO electrode of the above organic EL device as theanode and the Al/Li electrode layer as the cathode, a direct electricfield was applied between the electrodes in the atmospheric air to causethe organic EL device to emit light. At a voltage of 18 V or so,emission of light was observed for the organic EL device 1. Emission ofgreen light due to coumarin 6 was observed at the area into whichcoumarin 6 had been injected, and that of blue light due to PVK at thearea other than the area of green light emission.

Example 2

[0111] (Preparation of Source Film)

[0112] A polybutylmethacrylate (manufactured by Aldrich ChemicalCompany, Inc., molecular weight: 3.4×10⁵) containing 5% by weight ofcoumarin 6 (manufactured by Nippon Kankoh Shikiso, K.K.) was dissolvedin chlorobenzene, and a layer having 2 μm thick was produced on a quartzsubstrate by a spin coating method.

[0113] (Preparation of Target Film)

[0114] A target film was produced in the same manner as in Example 1.

[0115] (Molecular Implantation)

[0116] A test piece, constituted of two films obtained above being incontact with each other, was fabricated, and, from the direction of thetarget substrate, the test piece was irradiated with third harmonic ofYAG laser (wavelength: 355 nm, pulse width: 3 ns, irradiation energy perunit area: 20 mJ/cm², beam diameter: 1.8 mm) 10 times through a pinholehaving a diameter of 1 mm.

[0117] (Organic EL Device)

[0118] A 200 nm thick Al/Li electrode layer (manufactured by KohjundoKagaku, K.K.; Li content: 0.78% by weight) was formed on themolecular-implanted target film by vacuum deposition to provide anorganic EL device. With the ITO electrode of the above organic EL deviceas the anode and the Al/Li electrode layer as the cathode, a directelectric field was applied between the electrodes in the atmospheric airto cause the organic EL device to emit light. At a voltage of 18 V orso, emission of light was observed. An emission form (shape) reflectedthat of light interference generated on the occasion when YAG laser beampassed through the pinhole, and emission ring pattern being greenconcentrically was observed. In an area without molecular implantation,emission of blue due to PVK was observed, and in an area with molecularimplantation, emission of green light due to coumarin 6 was observed.

1. A process for producing a material, for an organic electroluminescentdevice, having an emission center, which comprises implanting anemission center-forming compound constituting a source into a targethaving at least one function selected from the group consisting of anelectron-transporting function and a hole-transporting function byirradiating a laser beam, and wherein (1) the laser beam and at leastthe target are relatively moved with irradiating the beam to form theemission center with a predetermined pattern, or (2) the emission centerat an area, corresponding to an interference pattern of an interferencelight, of the target is formed by irradiating the interference light ofthe laser beam.
 2. A process according to claim 1, wherein, in themethod (1), the source and the target being in contact with each otherare moved relative to the laser beam for forming the emission centerwith a predetermined pattern.
 3. A process according to claim 1,wherein, in the method (1), the irradiation is conducted through awaveguide.
 4. A process according to claim 1, wherein, in the method(1), the irradiation is conducted with the use of an optical fiber.
 5. Aprocess according to claim 1, wherein, in the method (1), the laser beamand the target are relatively moved with irradiating the beam and withmoving the source relative to the beam for forming the emission center.6. A process according to claim 1, wherein, in the method (2), a laserbeam from a single light source is split into a plurality of light pathsto cause the interference by an optical path difference.
 7. A processaccording to claim 6, wherein the interference is caused by introducingthe laser beam into a hole or a slit.
 8. A process according to claim 6,wherein the interference is caused by reflecting the laser beam througha plurality of reflection paths.
 9. A process according to claim 1,which comprises irradiating the laser beam with an intensity of or belowthe ablation threshold value of the source.
 10. A process according toclaim 1, wherein the laser beam comprises a pulse laser beam.
 11. Aprocess according to claim 10, wherein, in the method (1), the laserbeam and the target are relatively moved with synchronizing the beamwith a cycle of the pulse.
 12. A process according to claim 1, whereinthe target comprises an organic polymer.
 13. A process according toclaim 1, wherein the target comprises a compound having at least onefunction selected from the group consisting of the electron-transportingfunction and the hole-transporting function, and a film-formable organicpolymer.
 14. A process according to claim 13, wherein the compoundcomprises at least one compound selected from the group consisting of anoxadiazole derivative having the electron-transporting function, and anaromatic tertiary amine having the hole-transporting function.
 15. Amaterial for an organic electroluminescent device, which is obtainableby a process recited in claim
 1. 16. An organic electroluminescentdevice which comprises a pair of electrodes, and a material recited inclaim 15 which is interposed between the electrodes.
 17. An organicelectroluminescent device according to claim 16, wherein a single layerformed with a material in claim 12 is interposed between the pair ofelectrodes.